HDU 1506 largest Rectangle in a histogram (to find the largest rectangle)

1. Note To define a[] as LL, I'm here wa n times

2. When looking for boundaries, use DP thinking

AC Code:

#include <cstdio> #include <cstring> #define LL long longusing namespace Std;const ll inf=1<<60; LL a[100005];//to be defined as Llint l[100005];int r[100005];int main () {    int n;    while (scanf ("%d", &n), N)    {for        (int i=1;i<=n;i++)        {            scanf ("%lld", &a[i]);        }        for (int i=1;i<=n;i++)//With DP thought, continuously expands the boundary        {            l[i]=i;            while (L[i]>1&&a[l[i]-1]>=a[i])                l[i]=l[l[i]-1];        }        for (int i=n;i>=1;i--)        {            r[i]=i;            while (R[i]<n&&a[r[i]+1]>=a[i])                r[i]=r[r[i]+1];        }        LL Ans=-inf;        for (int i=1;i<=n;i++)        {            LL temp=a[i]* (r[i]-l[i]+1);            if (ans<temp)                ans=temp;        }        printf ("%lld\n", ans);    }    return 0;}

Do not use DP thought to find the boundary of the timeout code:

#include <cstdio> #include <cstring> #define LL long longusing namespace Std;const ll inf=1<<60; LL a[100005];int l[100005];int r[100005];int Main () {    int n;    while (scanf ("%d", &n), N)    {for        (int i=1;i<=n;i++)        {            scanf ("%lld", &a[i]);        }        for (int i=1;i<=n;i++)//timeout, use DP thought to optimize        {            int j=i;            while (J>1&&a[j]>=a[i])                j--;            l[i]=++j;        }        for (int i=1;i<=n;i++)        {            int j=i;            while (J<n&&a[j]>=a[i])                j + +;            r[i]=--j;        }        LL Ans=-inf;        for (int i=1;i<=n;i++)        {            LL temp=a[i]* (r[i]-l[i]+1);            if (ans<temp)                ans=temp;        }        printf ("%lld\n", ans);    }    return 0;}

Hdu 1506 largest Rectangle in a histogram (to find the largest rectangle)